Purification of cytochrome b-561 from bean hypocotyls plasma membrane. Evidence for the presence of two heme centers

• Published in: Biochimica et biophysica acta Vol. 1468; no. 1; pp. 1 - 5
• Main Authors: Trost, Paolo, Bèrczi, Alajos, Sparla, Francesca, Sponza, Giorgio, Marzadori, Beatrice, Asard, Han, Pupillo, Paolo
• Format: Journal Article
• Language: English
• Published: Netherlands Elsevier B.V 29.09.2000
• Subjects: Ascorbate; Cell Membrane - chemistry; Chromatography, Ion Exchange; Cytochrome b Group - chemistry; Cytochrome b Group - isolation & purification; Cytochrome b-561; Electrophoresis, Polyacrylamide Gel; Fabaceae - chemistry; Heme - chemistry; Hypocotyl - chemistry; Phaseolus vulgaris; Plants, Medicinal; Plasma membrane redox; Potentiometry; Redox titration; Spectrophotometry; Cytochrome b-561; Plasma membrane redox; Ascorbate; Redox titration; Phaseolus vulgaris
• ISSN: 0005-2736; 0006-3002; 1879-2642
• DOI: 10.1016/S0005-2736(00)00283-2

The high potential, ascorbate-reducible b-type cytochrome of plant plasma membranes, named cytochrome b-561, has been purified to homogeneity from etiolated bean hypocotyls. The pure protein migrated in denaturing electrophoresis as a broad band of approximately 55 kDa, and was found to be glycosylated. Optical redox titrations of partially purified cytochrome b-561 indicated that it contains two hemes with similar spectral features, but distinct midpoint redox potentials ( E m7+135 mV and +206 mV, respectively). The presence of two heme centers in cytochrome b-561 is consistent with its role in electron transfer across plant plasma membranes.